ISRAELI TANKS, TROOPS KILL 12 PALESTINIANS

Israel sent armored columns storming into the northern Gaza Strip and this West Bank city on Wednesday, killing at least 12 Palestinians as troops clashed with gunmen, demolished metal shops and homes and searched for suspects.

Violence spiraled through the day. After Israel withdrew its forces from Gaza, Hamas broke a three-week lull in such attacks and fired at least three rockets from northern Gaza at the Israeli town of Sderot, wounding an Israeli man.

Also in Gaza, a suicide bomber from Hamas blew himself up near an Israeli tank.

In the West Bank city of Jenin, a Palestinian militant from Yasser Arafat's Fatah faction was killed when his car exploded. His organization, Al Aqsa Martyrs Brigade, called his death an Israeli assassination.

In keeping with the pattern of such incursions, Israeli forces withdrew from Gaza after only a few hours, but here in Nablus they settled in for a longer mission, imposing a curfew on its old city as soldiers searched from house to house.

Gunshots and percussion grenades cracked as boys and young men, in the smoke of burning tires, smashed concrete blocks into smaller stones to fling at tanks and armored vehicles.

Two Palestinians were shot dead in Nablus and 20 were wounded, Palestinian hospital officials said. The army said soldiers had fired at one man who flung a firebomb at them and at another who fled and ignored warning shots after being ordered to stop.

Palestinians identified one of the dead as a 16-year-old stone-thrower and the other as Nasser Abu Safiyeh, 32, who was walking from prayers with his 93-year-old father, Mustafa Abu Safiyeh.

Wednesday's violence followed separate meetings in London by Palestinian and Israeli delegations with representatives of the United States, the United Nations, European Union and Russia -- the so-called Quartet -- about possibly resuming a peace effort.

In northern Gaza and here, officials of Arafat's Palestinian Authority have recently been working to reduce the violence, Israeli officials have said. They credited Palestinian security forces with stopping the firing of rockets at Israeli targets but discounted that as a small step intended only to forestall Israeli military movements into Gaza.

On Saturday, near a Jewish settlement in Gaza, Hamas blew up an Israeli tank, killing the four soldiers inside. Israel's defense minister, Shaul Mofaz, said afterward that Hamas "must be struck down." The army said its incursion into Gaza on Wednesday was aimed at destroying metal shops that manufacture rockets and mortars for Hamas.

As for the move into Nablus, the army said it was part of a broader operation that has been under way here for months.

Some militants in Nablus said they had agreed to the Palestinian Authority's limited cease-fire but no longer felt bound by their commitment.

"You should expect an attack now," a leader of Al Aqsa Martyrs Brigade said as he met with representatives of other Palestinian factions to discuss a response.